In a study to investigate the effect of regular exercise on raising HDL (good cholesterol) levels, a random sample of five male subjects known to have low HDL levels had their HDL measured. after six months on a regular exercise schedule, it was measured again. The data are given in the following table. The standardized value z of the Wilcoxon signed rank test W⁺is: A)0.4. B)0.95. C)1.48. D)3.51.

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The Wilcoxon signed-rank test is used to test the hypothesis that two related samples come from the same population. In this case, the null hypothesis is that there is no difference in HDL levels before and after the exercise program. The Wilcoxon signed-rank test is a non-parametric test, which means that it does not assume that the data are normally distributed. The standardized value z for the Wilcoxon signed-rank test for this data is 1.48, which corresponds to a p-value of 0.14. Since the p-value is greater than 0.05, we fail to reject the null hypothesis and conclude that there is no significant difference in HDL levels before and after the exercise program.

In a Study to Investigate the Effect of Regular Exercise